On the measurement of half-value layer in film-screen mammography.
Sources of variations in the measurement of half-value layer (HVL) in film-screen mammography are evaluated. Two principal sources are the energy responses of ionization chambers and the elemental compositions of the 1100 aluminum-alloy attenuation materials. Methods in measuring the thickness of attenuation materials are also an important potential source of error. These factors as well as the influence of geometry of measurement, position of measurement in the field, and precision of radiation output are examined. Recommendations for consistency in measurement are provided.
Wagner
L K
LK
University of Texas Medical School, Department of Radiology, Houston 77030.
Archer
B R
BR
Cerra
F
F
D055592:Biophysical Phenomena; D001703:Biophysics; D003627:Data Interpretation, Statistical; D005260:Female; D006801:Humans; D008327:Mammography / Q000295:instrumentation / Q000706:statistics & numerical data*